With development of society, kinds of safety problems occur increasingly, and accordingly, users pay more attention to security. Nowadays mobile terminals such as smart phones or tablet computers are widely used. Creating a strong password and maintaining a password protection of private documents are often required to these terminals, and all these actions involve secure password creation. Accordingly, safely creating passwords becomes very important, and application of the same to aspects of life and work has been found gradually. For example, to a mobile terminal, a display screen based on touch-feedback principles is generally provided. Password creating may be done by inputting numbers, letters, or other characters through touching of the keys. It might also be done by capturing the photo of a specific person's face, or drawing a particular pattern in a nine-grid screen. All of these methods suffer from serious drawbacks. For example, inputting by touching the keys and drawing the pattern in the nine-grid screen are subject to being seen by others and then being cracked. Creating a password by taking a photo of the user can possibly be cracked by a static graphics. Apparently, these prior art methods all lack sufficient security and reliability.